Rotatable ink storage and metering cartridge



Jan. 27, 1970 H. TRAMPOSCH 3,491,685

RbTATABLE STORAGE AND METERING CARTRIDGE M S 1 mw m a mm m e 5 WW 0 mm a7 y m i T m 0 LL 1 A s m m. 3 6M 0 T A R m 7 A 6 S 9 l z 4 I 2 v. m d m0 M Q m 8 6 2 O 4 women m =n u rm nwkmommnm 05a: mo mwIuZ Jan. 27, 1970H. TRAMPOSCH 3,491,685

S HOTRTABLE INK STORAGE AND METERING CARTRIDGE 2 Sheets-Sheet 2 allFiled May 24. 1967 INVENTOR. jrfierz Tram 00506 KTTOANEY United StatesPatent C) 3,491,685 ROTATABLE INK STORAGE AND METERING CARTRIDGE HerbertTramposch, Riverside, Conn., assignor to Pitney-Bowes, Inc., Stamford,Conn., a corporation of Delaware Filed May 24, 1967, Ser. No. 640,871Int. Cl. B41f 31/00, 31/02; B05c 1/06 US. Cl. 101-350 7 Claims ABSTRACTOF THE DISCLOSURE An ink dispensing cartridge composed of a first foammaterial with large pores constituting an ink reservoir and a secondfoam material with smaller pores positioned in contact with the firstfoam and exposed to a portion of the exterior of the cartridge toprovide ink to an applicator roller.

This invention relates in general to a printing apparatus and inparticular to apparatus for containing ink and for applying ink to aprinting roller or the like.

More specifically the invention is concerned with a cartridge adapted tocontain a supply of ink and to meter the ink to an intermediate orapplicator roller in .quantities which maintain the applicator roller ata uniform saturation level suflicient to adequately apply ink to aprinting drum or indicia and yet insufficient to bleed or drip ink fromthe surface of the applicator. This invention is also specificallyconcerned with apparatus which prevents the ink supply from dripping,leaking or over feeding the intermediate roller when not in use.

Conventional inking devices are of two types, one wherein a reservoir ofink is connected to the applicator roller by a wick which throughcapillary action provides a continuous quantity of ink to the applicatorroller. The second type of inking device is one in which an absorbentmember such as felt is pre-saturated with a quantity of ink and whichthrough contact with an applicator roller provides a continuous thoughdiminishing amount of ink to the applicator. The first type has theadvantage of having a large quantity of ink available for the applicatorhowever it also has the disadvantages of having a body of free ink whichupon movement will tend to overload the wick member and produce bleedingor dripping. This disadvantage of the felt rollers has been theinability to provide a constant or uniform ink supply over the life ofthe roller. When the applicator is new the felt tends to be saturatedand produce a bleeding or dripping situation and as ink is depleted thepercentage of the saturation at the outside of the felt continuallydiminishes in proportion to the ink used. The present invention combinesthe best features of both prior art devices in that it provides a largesupply or reservoir of ink and advantages of the felt type of applicatorWithout the problems of bleeding and rapid diminishing of surfacesaturation over the life of the applicator.

It is also a problem in conventional inking devices that the inkprovided to the applicator roller and to the printing member usuallydiminish slightly for each print that is made and thus it is not readilydiscernible when the applicator is low on ink or should be replaced. Thepresent invention provides a means to maintain the inkingcharacteristics nearly constant throughout the useful life and then acomparatively rapid drop off in inking characteristics when the supplyof ink has been diminished to the point where the ink cartridge shouldbe relaced. Thus an operator becomes immediately aware that his inksupply is low and must be replenished.

Additionally the conventional inking devices are in continuous contactwith the applicator roller and tend to supply ink to the applicatorduring the periods when the printing apparatus is not in use. This typeof arrangement tends to oversaturate the applicator roller and produceeither bleeding or excessive inking during the first few cycles ofoperation after prolonged shutdown. The present invention provides asimple and effective disengagement device to prevent the possibility ofthe applicator roller and the ink supply from being in ink transferringcontact during the shutdown periods of the apparatus. The only time theapplicator roller is in contact with the ink supply is during theoperation of the device.

The degree of surface saturation of the intermediate or applicatorroller which applies ink to the printing member is critical to theamount of ink that is deposited on the printing member in each cycle ofoperation. It is important to maintain the surface saturation at thecontrolled level. The level of saturation of the applicator roller iscontrolled by the surface saturation level of the ink supply memberwhich contacts or supplies ink to the applicator roller and the lengthof time the applicator roller is in contact with the supply member. Thesaturation level of the surface of the ink supply must be higher thanthe saturation level of the surface of the applicator roller so that inkflows from the ink supply member to the applicator member. Also thecontact between the member must be sufficient to allow the amount of inkused on each printing cycle to be replaced.

It is an object of this invention to improve inking cartridges used inprinting apparatus to provide an ink supply with a uniform surfacesaturation over an extended period of use.

It is also an object of this invention to increase the useful life ofinking cartridges and to provide a large supply of ink in an easilyhandled form.

It is also an object of this invention to control the surface saturationcharacteristics of inking devices used in printing apparatus.

It is also an object of this invention to provide an ink applicatorcartridge which will hold large quantities of ink and maintain uniformsurface saturation characteristics as the internal percentage ofsaturation decreases.

It is also an object of this invention to provide an ink cartridge whichdoes not bleed or drip during inoperative periods.

It is also an object of this invention to provide apparatus whichdisengages an applicator roller from an ink supply when the printingapparatus is not in operation.

It is also an object of this invention to provide an ink cartridge for aprinting apparatus having an increased ink capacity and surfacecharacteristics which provide uniform inking during the effective lifeof the cartridge and a rapid fall off of the amount of ink transferredwhen the effective life of the cartridge has been exceeded.

BRIEF SUMMARY These and other objects of this invention are obtained bymeans of an inking cartridge having an inner core of porous materialsuch as polyurethane in the free and uncompressed or slightly compressedstate to contain a large quantity of ink and a surrounding layer of thesame or similar porous material compressed to about 10% of its free formto provide a high surface saturation. The cartridge completely enclosesthe porous member except for a small window which when the cartridgerotates, contacts a porous applicator roller. The applicator roller ismounted in a loose bearing which leaves the roller out of contact withthe cartridge except during operation of the printing apparatus.

For a better understanding of the invention as well as other objects andfurther features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawing.

DESCRIPTION OF DRAWINGS FIGURE 1 is an isometric view of an inkapplicator embodying the present invention.

FIGURE 2 is a sectional view of the ink cartridge taken along lines 2-2of FIGURE 1.

FIGURE 3 is a sectional view of the ink cartridge taken along lines 3--3of FIGURE 2.

FIGURE 4 is a side view of the ink cartridge and applicator embodyingthe present invention.

FIGURE 5 is a graph showing the relationship between capillary forcesand foam saturation.

FIGURE 6 is a sectional view of an ink cartridge showing an alternateembodiment of the invention.

DETAILED DESCRIPTION Referring to the drawings, there is shown in FIGURE1 an ink cartridge assembly embodying the present invention. FIGURES 2and 3 show sectional views of the cartridge exposing the internalarrangement of foam like material adapted to contain printing ink. Theouter shell 10 of the cartridge is constructed of plastic or some othersuitably rigid, ink impervious material. The shell 10 is cylindricallyshaped with one end closed and having one or more openings 12 located inthe closed end. There is an enclosing cover 14 adapted to seal the openend of the cylinder. The shell 10 and the cover 14 have aligned/ sizedcenter holes to receive a center shaft 16. The shaft 16 has splined endswhich are sized for a tight fit into the aligned holes in the shell andthe cover so that when the shaft is forced into the opening in the shell10 and the cover 14 is forced down over the shaft the entire assembly isheld secured. The holes for the shaft are in a pair of bearing surfaces18 and 20 in the shell 10 and cover 14 respectively. The bearing 18 isjournalled in a slotted bearing plate 22 and the bearing 20 isjournalled in a slotted bearing plate 24: The entire assembly is held inthe bearings by means of a spring loaded clip member 26 biased againstthe bearing 20 by means of the tension spring 28.

The cartridge 10 is shaped so that the end adjacent the cover 14 isenlarged providing a raised surface or shoulder 30 around a portion ofthe circumference of the cartridge As seen in FIGURE 1 there is anopening 32 in the surface 30. An applicator roller 34 is rotablysupported from the bearing plate 24 in position for its surface to be incontact with the raised surface 30 of the cartridge 10 and to come intocontact with the opening 32. The applicator roller 34 is constructed ofa porous or foam material, for example polyurethane, which is suitablefor holding and retaining liquids such as ink. The entire assemblyincluding the cartridge 10 and the applicator roller 34 are positionedto be in contact with a printing drum or indicia 36 shown in dottedlines in FIG. 4. The printing drum 36 has raised metal letters on acurved portion of the surface thereof so that when the drum rotates themetal lettors are in contact with the surface of the applicator roller34. The remaining portion of the drum 36 is undercut so that the surfaceof the applicator roller is not in continual contact with the surface ofthe drum. Rotation of the drum 36 causes rotation of the applicatorroller 34 and in turn forces the applicator roller against the surface30 of the cartridge 10 and produces rotation of the cartridge.

The applicator roller 34 is mounted on a tube 38 which is journalledabout a rod 40 mounted in the bearing plate 24. The tube 38 is oversizedor larger than the rod 40 so that when the tube 38 rests on the rod 40the applicator roller 34 is not in contact with the surface of thecartridge 10. However when the printing drum 36 rotates against thesurface of the applicator roller 34 the roller is forced upward aroundthe rod 40 into a position wherein the surface of the applicator roller34 is in contact with the surface of the cartridge 16. The applicatorroller 34 will remain in this upward position for the duration of theprinting cycle of the drum 36. At the completion of the printing cyclethe printing drum disengages from the applicator roller 34 allowing theroller 34, under the force of gravity to fall downward around the rod 40and return to its original position out of contact with the surface ofthe cartridge 10. If the applicator roller 34 stopped in contact withthe hole 32 then the ink would tend to flow from the cartridge to theapplicator. After a period of time the saturation level of theapplicator would increase to a point where overlinking would occur onthe succeeding inking cycles. By removing the applicator roller fromcontact with the cartridge when it is not in use the possibility of theapplicator being in contact with opening 32 is eliminated.

The inside of the cartridge 10 is completely filled with a porous foammaterial as for example polyurethane. Two different types or conditionsof foam are used. The center portion or the bulk of the foam consists offoam material 50 which is referred to herein as uncompressed but whichactually may be slightly compressed when it is placed in the cartridgeand which is capable of holding large quantities of ink. The enlargedportion of the cartridge 10, that is the portion under the surface 30,contains a peripheral layer of compressed foam 52 as seen in FIGURES 2and 3. The foam 52 may be of the same material as the foam 50 with theexception that the foam 52 is not in the free or uncompressed state buthas been compressed to a portion of its original size. It is notnecessary that the compressed foam extend completely around theperiphery of the shell but only to the extent necessary to cover theopening 32. FIGURE 6 shows a cartridge with a smaller compressed foamsection 52.

Since the foam 5 3 is in the uncompressed state the porous openings arelarger than the openings in the compressed foam 52. That is thepercentage or amount of void space in the uncompressed foam is largerthan the percentage of the available void space in the compressed foam.Therefore, not only is the uncompressed foam capable of retaining alarger quantity of ink due to the larger mass of foam involved but italso is capable of retaining a larger volume of ink per unit volume offoam than the compressed foam. Inversely however, as explained below,the capillary action produced in the uncompressed foam is considerablyless than the capillary action in the compressed foam. That is thepercentage of ink saturation at the interface of the foams variesbetween the compressed and uncompressed foam as shown in the graph ofFIG- URE 5.

The purpose of the uncompressed foam 50 is to act as an inkreservoir andthe purpose of the compressed foam 52 is to maintain a uniformsaturation level at the surface of the foam, and thus a uniformsaturation of the applicator roller 34 and uniform printing for eachcycle of operation.

In relief printing wherein ink is applied to the surface of raised orrelief characters and transferred from the characters to the printedsurface, a very important feature is the uniformity of the applicationof ink to the surface on which the printing is to appear. In order tohave a uniform density of printed characters on the final sheet it isnecessary that the application of ink to the printing member be uniform.As shown herein a printing roller or drum 36 is coated with ink by anapplicator roller 34 and then the ink is transferred in the form ofprinting to sheets of paper or the like. If the surface saturation ofthe applicator roller 34 is maintained at a uniform level then for eachrotation of the printing member 36 a uniform amount of ink will bedeposited from the applicator roller 34 onto the surface of raisedcharacters on the printing drum 36. If the applicator roller 34 is notcontinually replenished with ink then each succeeding printing cyclewill receive slightly less ink than the previous one and over anextended period of time would deplete the ink from the applicator roller34. When it is determined what level of saturation the surface of theapplicator roller 34 should be at in order to apply a uniform coating ofink onto the printing drum 36 in quantities sufficient to provide thedesired ink density in the printing process, it is then possible todesign an ink cartridge to maintain the surface saturation of theapplicator roller 3-4 at the desired uniform level.

One means of controlling the amount of ink which is transferred from theink cartridge to the applicator roller 34 is to control the amount oftime that the applicator roller is in contact with the exposed portionof the foam in the cartridge. For example the opening 32 could beextended so that the applicator roller 34 is in contact with the foamfor a longer period of time and thus more ink would be transferred tothe applicator roller for each cycle of operation. If less ink weredesired then the size of the opening 32 would be smaller.- The opening32 could be theoretically extend completely around the cartridge and theapplicator roller would be constantly in contact with the ink applyingfoam during operation of the apparatus. In the embodiments shown hereinit was determined that the amount of ink depleted by each printing cycleis essentially replaced by having the applicator roller in contact withthe foam for the length of time permitted by an opening of the sizeindicated by opening 32.

The foam 50 in the ink cartridge consists of a cellular or porousmaterial in which series of small cells or pores interconnect to form asponge like material. When the foam material is partially immersed in aliquid the pores which are interconnected tend to act as thin tubesproducing capillary action which draw fluid up into the foam against theaction of gravity. The larger the cells or pores the smaller thecapillary forces produced; in the same manner the smaller pores tend toproduce larger capillary forces. The action of the capillary forces isnot exactly the same as it would be in a tubular member since the cellsor pores are not uniform in size, are not regularly interconnected andare more or less randomly dispersed throughout the foam. However thecapillary.

forces that do exist have the same characteristics as those created inuniform tubular structures and for discussion purposes will beconsidered as essentially the same.

The curve labeled Uncompressed Foam in FIGURE 5 represents therelationship between the height liquid is held in the foam by capillaryaction and the amount of saturation of the liquid in the foam at thatlevel. The curve was derived by placing a column of the uncompressedfoam .material, saturated with ink, in a reservoir of liquid ink andmeasuring the height at which the ink was held by capillary action andmeasuring the amount of saturation of ink at the various height levels.For example it can be seen at 0 inches above the fluid level, or wherethe foam is immersed in the fluid, the saturation is 100%; at a heightof one inch above the liquid the foam is 96% saturated with ink. At aheight of two inches above the ink the foam is 70% saturated with inkand the degree of saturation tends to fall off very rapidly from the oneinch to the three inch level. At the 4.8 inch level the foam isapproximately 15% saturated with ink. The second curve in FIGURE 5,entitled Foam Times Compressed in Volume shows, how the compression ofthe foam which produces smaller cellular structures, creates the highercapillary forces. It can be seen from the curve that the capillaryforces will hold ink at a height of 12 inches above a liquid level andhave a 15% saturation at the point. It can also be seen that thepercentage of saturation remains very high in the compressed foam up tothe height of 7 inches at which point it is 96% saturated. Between 7 and12 inches the percentage of saturation falls oif rapidly in the samemanner as it did for the uncompressed foam.

When different types of foam or foams having different degrees ofcompression or cellular structure are placed in contact, the pressuresproduced by capillary action at the boundaries of the two materials isthe same. Thus for example if the surface of the uncompressed foam is70% saturated that is it is operating at a capillary pressure suflicientto sustain 2 inches in height of ink, then compressed foam, in contactwith the surface of the uncompressed foam, at that point, would also beat the same capillary pressure, however the percentage of ink saturationat that pressure is 99% for the compressed foam. This is shown on thegraph by tracing across on the 2-inch line until the uncompressed foamcurve is intersected then reading down at the bottom 70%; thencontinuing across on the 2-inch line until the compressed curve isintersected and reading 99% at the bottom.

It can be seen from the curves that as the ink is depleted from theuncompressed foam the degree of saturation falls off rapidly, howeverthe compressed foam though undergoing the same pressure drop, maintainsa relatively high or uniform degree of saturation.

For purposes of example, if the foam 50 is saturated to approximately ofits total capacity prior to use then the compressed foam receives inkfrom the uncompressed foam and maintains a surface saturation ofapproximately 99%. In printing operations, the compressed foam whichappears in the opening 32 tends to be depleted of ink by the applicatorroller 34 but because of the capillary forces draws ink from theuncompressed foam 50. The saturation of the uncompressed foam 50 dropsaccording to the curve in FIGURE 5 and by tracing horizontally across tothe uncompressed foam curve the saturation level of the compressed foamcan be determined. It can be seen that the saturation level of thecompressed foam is always going to be between 98 and 100% during theentire time that there is ink left in the uncompressed foam. Of courseit is realized that due to the cellular nature of the foam materialthere are pockets of ink which will not be removed by capillary actionand thus there will be ink remaining in the foam even though thepercentage of saturation of the compressed foam has fallen below 98%. Atthe point that the uncompressed foam is essentially depleted of ink thecompressed foam still is at the 98% saturation and will continue toprovide ink at a farily uniform rate. Since the compressed foam does nothold the quantity of ink that the uncompressed foam holds the number ofcycles that can be operated based on amount of ink stored in thecompressed foam is considerably less. However for a period of time thecompressed foam will function with a surface saturation in excess of96%. When the saturation of the compressed foam reaches the 96% pointthe fall off in ink supply or degradation in the printing is ratherrapid, as seen by the top of the curve for the compressed foam. Thisrapid fall of foam from a maximum saturation to an unacceptablecondition for printing is advantageous to the operator of the printingapparatus. In conventional printing devices the images deteriorate veryslghtly for each cycle and -thus are not readily noticeable by theoperator. According -to the present invention the rapid fall off in thequantity of ink provided indicates to the operator that the cartridgemust be replaced with a new supply of ink. In the embodiment shown inFIGURE 6 the amount of compressed foam is less thus the amount of inkavailable after the main supply has been depleted is less. In this casethe drop in print quality is more rapid and more noticeable.

OPERATION In the embodiment shown herein the compressed foam 52 isplaced around a portion of the inner surface of the shell 10 in aposition to cover the Window or opening 32. It should be noted hereinthat the foam 52 may or may not be the same material as the foam 50. Thebasic requirement is that the foam 52 have a smaller cellular structurethan the foam 50 and thus produce the higher saturation characteristicsas seen by the curve in FIGURE 5. For example the material may be thesame and may be compressed to one-tenth of its original size, as is thematerial used to construct the curves shown in FIGURE 5. However if thematerial were only compressed to one-fifth the original size thecharacteristics would be similar but its saturation curve would fallbetween the two curves shown in FIGURE 5, and though the basic theory ofoperation would be the same, the degree of uniformity of the surfacesaturation of the material in the opening 32, throughout the effectiveoperational life of the cartridge, would be less. If on the other hand amaterial was used with smaller pores or were more highly compressed thanthe foam used in the curve shown in FIGURE 5, then its saturation curvewould be displaced upwards, thus the surface saturation 'would be morenearly uniform throughout the life of the cartridge. It has been foundhowever for useful practical purposes the foam compressed to one-tenthof its uncompressed size can be easily manufactured and provides adegree of uniformity throughout the life of the cartridge which is veryeffective. It is however within the scope of this invention to vary thepore structure and size of the foam materials to provide the capillarycharacteristics desired.

In order to fill the cartridge with ink there are holes 12 located inthe closed end of the cartridge. The cartridge may be placed in a supplyof liquid ink with the holes submerged below the surface of the ink. Avacuum pulled on the open end of the cartridge will draw ink through theholes into the foam material up into the cartridge. The vacuum is helduntil the cartridge reaches 90% saturation. The cover 14 is then placedon the cartridge so that the shaft 16 lies in the opening and holds thecover secured on the cartridge. Obviously the cartridge may be filled byother means such as pouring ink into the foam or immersing the cartridgein ink. The holes 12 also provide vents so that the interior of thecartridge is always at atmospheric condition.

What is meant by the cartridge being 90% saturated is that the averageink content of the foam at rest within the cartridge when it is placedin the position in which it will operate within the printing machine is90% or the maximum amount of ink the foam can hold. In this conditionthe bottom of the foam material is very nearly at 100% saturation. Ifthis is the case then obviously the top of the foam is at a point lessthan saturation and the interior of the foam varies between the top tothe bottom condition. The average saturation is approximately 90% andthe increase due to the centrifugal force during operation does notexceed 100%. It should be noted that the optimum size of the cartridgeis to have the diameter of the cartride the same as the length. If thelength exceeds the diameter then during shipping or at other times whenthe cartridge stands on end, the column of ink which is supported bycapilliary force is greater than that which is supported when it standson its side in the machine. Therefore a portion of the cartridge willexceed the 100% saturation condition when stood on end and bleeding ordripping of ink will occur. If however the length and the diameter arethe same then the same average condition exists through-out in allorientations of the cartridge.

When the cartridge is filled with ink and properly placed in a machinethe applicator roller is in a position to receive ink through theopening 32 in the shell 10. The material from which the applicatorroller is constructed is also a foam material and very probably the samefoam as the compressed foam 52. The applicator roller 34 is inked to asaturation level sufficient to apply the proper amount of ink to theprinting drum 36. As the printing drum 36 rotates the printing surfacecomes in contact with the applicator roller 34 forcing the roller upagainst the shell rotating the cartridge. Ink is deposited from theapplicator roller 34 onto the raised metal characters of printing drum36 and at the same time receives approximately the same amount of inkfrom the compressed foam 52 in the opening 32 in the cartridge 10. Ifthe surface saturation of the compressed foam '52 is maintained fairlyuniform then the amount of ink that is transferred during each cycle ofoperation between the compressed foam 52 and the applicator roller 34 isalso uniform. The operation can be repeated until the entire availableink supply from the uncompressed foam 50 is used up and the remainingamount of ink in the compressed foam is also used. As can be seen fromFIG. 5 the saturation of the compressed foam varies between 98 and 100%of saturation during the effective life of the uncompressed foam. Beyondthat point there is still good inking characteristics until the surfacesaturation of the compressed foam drops below the 97% point at whichtime the degradation in printing and ink transfer increases rapidly.

What is claimed is:

1. An inking device for use with a printing apparatus comprising (A) aframe (B) ink storage and metering means comprising 1) an ink imperviousshell member rotatably mounted on said frame and having an openingformed therein,

(2) a core of a first porous material having relatively large pores andcapable of holding a large quantity of ink positioned within the shellmember, and

( 3) a layer of a second porous material having smaller pores than saidfirst porous material and extending around a portion of said firstporous material in a position to be exposed by said opening, and

(C) applicator means rotatably mounted on said frame for intermittentcontact with said second porous material for receiving ink therefromthrough said opening when said applicator means contacts said secondporous material whereby said second porous material meters limitedquantities of ink from said first porous material to said applicatormeans.

2. A device as set forth in claim 1 wherein said core of first porousmaterial is the sole source of ink for said second porous material.

3. A device as set forth in claim 2 wherein said first porous materialis composed of substantially uncompressed polyurethane foam and saidsecond porous material is composed of polyurethane foam compressed tosubstantially 10% of its original size whereby said second porousmaterial maintains a substantially uniform saturation level of ink atsaid opening over substantially the entire time that there is inkremaining in said first porous material.

4. A device as set forth in claim 1 wherein said applicator meanscomprises a roller mounted on said frame adjacent said shell member inalignment with said opening and is adapted to be driven by a printingmember of said printing apparatus, said roller contacting said shellmember so as to rotate the latter when rotated by said printing member.

5. A device as set forth in claim 4 including means to prevent saidapplicator roller from remaining in contact with said shell member orsaid second porous material when said roller is not being rotated bysaid printing member.

'6. A device as set forth in claim 5 wherein said means to preventcontact between said applicator roller and said shell member or saidsecond porous material comprises a bearing supporting said applicatorroller on a shaft of smaller diameter than said bearing and at alocation below the axis of said shell member whereby said applicatorroller moves out of contact with said shell member or said second porousmaterial when said applicator roller is not being rotated by saidprinting member.

7. An inking device for use with a printing apparatus comprising (A) aframe (B) ink storage and metering means comprising (1) a substantiallycylindrical ink impervious shell member rotatably mounted on said frameand having an opening formed therein,

(2) a core of a first compressible porous material substantially fillingthe interior of said shell member, said material being in asubstantially uncompressed state and having relatively large porescapable of holding a large quantity of ink.

(3) a layer of a second compressible porous material extending around aportion of said first porous material and confined Within said shellmember adjacent said opening so as to be exposed therethrough, saidsecond porous material being in a substantially compressed state andhaving smaller pores than said first porous material, whereby saidsecond porous material draws ink from said first porous material due togreater capillary forces in the former,

(C) an applicator roller,

(D) means rotatably mounting said applicator roller on said frameadjacent said shell member in position to contact said second porousmaterial through said opening to receive ink therethrough from saidsecond porous material, said applicator roller being adapted to rotatesaid shell member and said core when said applicator roller is rotatedby a printing member of said printing apparatus, and

(E) means for maintaining said applicator roller out of contact withsaid second porous material where said applicator roller is not beingrotated by said printing member.

References Cited UNITED STATES PATENTS 3,066,603 12/1962 Talarico118-258 X 3,179,043 4/1965 Mellison 101349 3,194,155 7/1965 Davis101-367 X ROBERT E. PULFREY, Primary Examiner J. R. FISHER, AssistantExaminer U.S. Cl. X.R.

